Just what songs are part of the canon is a matter of some debate, as old songs are dropped and new songs are added all the time. Early canon songs like Tears for Fears "Shout" and Depeche Mode "People are People" had been dropped from the canon before some current CTYers were even born, and other songs, like "Birdhouse In Your Soul" by TMBG were added, though they hadn't been written yet in the early days of CTY. The only universal appears to be American Pie by Don McLean, which, according to many reports, has been the last song at every dance of every session of every site since at least the early or mid 1980's. Even relatively tradition poor sites, like Young Students and Baltimore play American Pie. Stairway to Heaven, the second most important canon song, has been played since at least 1984. Some sources say that for a long time, Stairway was the last song, and Pie the second to last, but when RAs couldn't find a copy of Pie, they played Stairway first, followed by Pie after they found it, and it stuck that way.
It is not entirely clear how the canon started. The best theory is that songs, some of which were popular at the time, started being played at dances, and eventually began to become a notable part of each dance. CTYers from the mid and early 80's remember American Pie being played at dances; however, they didn't seem to identify with it as the anthem of CTY as many CTYers from later days did. Because it was popular, however, it continued to be played at dances, until it eventually became equated with CTY in the minds of CTYers. Presumably, other Canon songs began in similar ways: they were played at the dances, CTYers liked them, so they continued to be played until they became as much a part of a CTY dance as PDA.
Another interesting tidbit of canon history is the Pie Callbacks. Often at dances, CTYers will shout specified things at certain points during American Pie. The most common is to shout "Die, Die, Die, Live, Live, Live, Sex, Sex, Sex, More, More, More" or some variation of that after Don McLean sings "And this will be the day that I die". This predates 1993, and reports of this occurring in the late 80's have been made.
Another canon related tradition is the shouting "Go Home, Nobody Loves You" followed by "We Love You!" after the last notes of American Pie have played, as the RAs herd students back to their dorms. This also predates 1993.
Jesters- One Lancaster Canon Tradition is "Jesters" for American Pie. The first "Jester" position was played by Aaron Tarnow (sometimes recognized as "the short kid with the funny hat"), in 1998, specifically acting out the part of the Jester during the song. There was no real Jester following that, until Ken Levin decided to reaffirm the position myself in 01.1, subsequently passing my hat on to another no-more for the next session. With the advent of the rule CTY imposed recently making it very difficult to take two Lancaster sessions in one summer, the role of the Jester is a one-session position and is to be passed down to another nomore of a particular session. The Jester wears a Jester's hat with bells on it as well as an old, ugly plaid sport jacket provided by Travis-Jason Feldstein while acting out his role.